<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html lang="en">
<head>
	<meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
	<title>变量类型</title>
</head>
<body>

    <script type="text/javascript">
        //var a=15;
        //alert(typeof a);       //number

        //var a='sdsda';
        //alert(typeof a);      //string


        // var a=true;
        // alert(typeof a);        //boolean

        // var a = function(){
        // 	alert('sadd');
        // }
        // alert(typeof a);         //function 


       // var a = document;
       // alert(typeof a);         //object
       // 
       
        //alert(typeof b);          //undefined


        var b;
        alert(typeof b);          //undefined

    </script>
	
</body>
</html>